液—固磁场流态化模型及普遍化相图

本文考察了磁场流态化的基本特征,并结合实验分析了均匀磁场中液-固流态化模型参数的变化规律,对Ma 和 Kwauk 提出的指数模型作了补充,使之与经典流态化加以统一,并在此基础上获得了磁场流态化的普遍化关系图。完善后的模型可根据经典流态化的基础数据直接预示磁场作用下流态化的一些特征,模型计算结果与水-钢丸系统的实验数据吻合较好。     

Production of biogenic amines by lactic acid bacteria and enterobacteria isolated from fresh pork sausages packaged in different atmospheres and kept under refrigeration

The occurrence of in vitro amino acid activity in bacterial strains associated with fresh pork sausages packaged in different atmospheres and kept in refrigeration was studied. The presence of biogenic amines in decarboxylase broth was confirmed by ion-exchange chromatography and by the presence of the corresponding decarboxylase genes by PCR. From the 93 lactic acid bacteria and 100 enterobacteria strains analysed, the decarboxylase medium underestimates the number of biogenic amine-producer strains. 28% of the lactic acid bacteria produced tyramine and presented the tdc gene. All the tyramine-producer strains were molecularly identified as Carnobacterium divergens. Differences on the relative abundance of C. divergens were observed among the different packaging atmospheres assayed. After 28 days of storage, the presence of argon seems to inhibit C. divergens growth, while packing under vacuum seems to favour it. Among enterobacteria, putrescine was the amine more frequently produced (87%), followed by cadaverine (85%); agmatine and tyramine were only produced by 13 and 1%, respectively, of the strains analysed. Packing under vacuum or in an atmosphere containing nitrogen seems to inhibit the growth of enterobacteria which produce simultaneously putrescine, cadaverine, and agmatine. Contrarily, over-wrapping or packing in an atmosphere containing argon seems to favour the growth of agmatine producer-enterobacteria. The production of putrescine and cadaverine was associated with the presence of the corresponding amino acid decarboxylase genes. The biogenic amine-producer strains were included in a wide range of enterobacterial species, including Kluyvera intermedia, Enterobacter aerogenes, Yersinia kristensenii, Serratia grimesii, Serratia ficaria, Yersinia rodhei, Providencia vermicola and Obesumbacterium proteus.     

还原氧化石墨烯/四氧化三铁纳米复合物的应用研究进展

还原氧化石墨烯/四氧化三铁(RGO/Fe_3O_4)纳米复合物是一种新型的磁性纳米材料,集Fe_3O_4和RGO的优点于一体,具备高比表面积、高稳定性、超顺磁性等优越的机械、电、热、光学特性,充分展现其在理论研究以及实际应用方面的价值和潜力。本文对近几年RGO/Fe_3O_4磁性纳米复合物材料在磁性固相萃取、锂电子电池、传感器材料、电磁波吸收、催化剂、酶的固定化、药物传输以及磁控开关方面的应用研究进展进行了综述,重点综述了RGO/Fe_3O_4磁性纳米复合材料在磁性固相萃取方面的应用研究,分析对象包括染料、金属离子、农兽药、增塑剂、抗生素以及生物大分子,展现出其在分离富集领域的巨大应用潜力。最后,提出RGO/Fe_3O_4纳米复合材料在研究中存在的问题,并对该材料的研究发展方向进行了展望。     

利用黄原胶与魔芋精粉的协同增效作用研制低温冷冻果馅

应用黄原胶与魔芋精粉的协同增效作用 ,对低温 (- 2 0℃ )冷冻果馅 (添加天然果汁 )进行了研究 ,采用葡萄糖浆与黄原胶、魔芋精粉复合使用 ,在其抗析水性及抗冻性方面取得了良好效果。     

Effectiveness of sweet ovine whey powder in increasing the shelf life of Amaretti cookies

The effect of sweet ovine whey powder on physical-chemical and textural changes during storage of Amaretti cookies is reported. The aim of the study was to study the impact of the ovine whey powder on the shelf life of cookies. Two batches of Amaretti cookies were prepared, with and without whey powder. Freshly baked Amaretti cookies were individually packaged with a high water vapour barrier film and stored for 120 days under controlled temperature/humidity conditions. Physico-chemical, textural and sensory changes were inspected at regular intervals during storage.The water-binding properties of ovine whey powder, as revealed by sorption isotherms and magnetic resonance imaging, resulted in delayed firming and increased shelf life of cookies with whey powder with respect to control cookies and did not influence the sensory properties. MRI allows visualizing differences in internal structure and proton distribution of the two batches of Amaretti cookies, pointing out the more homogeneous internal structure of the cookies where whey powder is added.     

畜禽鱼虾肉在‒18 ℃冻藏过程中营养价值的变化

冷藏是市场及居民普遍使用的肉类贮藏方法,在冷藏过程中肉会发生一些品质和营养方面的变化。本研究选择-18℃冷藏条件,以典型畜禽鱼虾肉为研究对象,选取猪、牛、羊、鸡、鱼和虾共六类肉样,通过厂家直供、超市和农贸市场途径共计采集16个样品。在冷藏过程中,每隔一段时间取出一包肉样品,对其各种指标进行测定和记录,研究肉品在冷藏期间发生的品质变化。实验结果表明,在-18℃下贮藏到360天,随着贮藏时间的延长,各种肉的感官评分均呈现下降趋势,肉的鲜度不断下降,畜禽肉评分均在6分及以上,鱼虾肉已低于6分。肉样品的pH值和水分含量均在标准范围内波动;蛋白质、脂肪及脂肪酸等营养成分含量均在小范围内波动,无明显变化趋势。     

MRI研究泠冻馒头微波复热过程水分的迁移变化

普通新鲜馒头在-18℃的环境中冷冻24h后，取出进行微波解冻加热实验。利用核磁共振成像（MRI）技术研究冷冻馒头复热过程中水分的迁移变化。馒头在受热过程中水分的损失直接影响馒头的品质。实验比较了冷冻馒头在微波蒸碗不加水和加水两种方式下含水量的变化，发现微波蒸碗加水复热对馒头的水分有一定的补偿效果。     

三相电动机绕组首末端反接时运行状态分析

通过讨论Y315M2-8电机的一起质量事故,分析三相异步电动机在其中一相绕组首末端反接情况下电机的运行状态.分析着重于电机的转向、三相电流及转速三个方面.     

低海拔地区纺织空调的节能探索

在新疆吐鲁番低海拔地区纺织厂空调系统调节过程中，根据室外干湿球温度变化差异，分析了室外空气与车间回风的焓差变化，大量使用新风，降低空调冷负荷，实现充分利用自然能源，从而达到节能的目的。并总结出不改变制冷机工况实现大温差小水量的简单方法。